Process for heat treating metals and alloys



Jan. 29, 1929. 1,700,547

w. s. SMiTH ET AL PROCESS FOR HEAT TREATING METALS AND ALLOYS Filed Nov. 21, 1925 I if 4 r- 1 9 /4 W INVENTORS: WILLOUGHBY STATHAM SMITH HENRY JOSEPH GARNETI JOHN ANGEL HOLDEN By their Attorneys,

Patented Jan. 29, 1929.

1 1,700,541 PATE OFFICE.

, WILLOUGHBY STATEAM SMITH, or NEWTON rorrLEroRnnE nY :rosnrn GARRETT, or SEVEN OAKS, AND JonN ANGEL HOLDEN, or GIDIEA rAnmnNeLANn.

rnocnss roa .HEAT TamTINe METALS AND ALLogs:

I Application filed November 21, 1925, Serial No. 70,678, and in Great liritain I 3, 1925.

This invention relates toprocess for heat treating metals and alloys in linear form composed of a wire, a tape-or a plurality of wires, tapes or tapes and wires forming a cable, and hereinafter alluded to under the generic term of a conductor, and more particularly to the annealing of loaded telegraph and telephone conductors.

It is well known that metals and alloys of metals, such as copper, deteriorate rapidly when heated in air or in the presence of re ducing gases, and even small quantities of such gases have a marked effect on their properties, and in order to develop the maximum permeability of theloading materiahit is usual to pass the conductor through a tube of refractory material placed inside a suitable furnace to which tube an inert gas,fsuch as nitrogen, is sup-plied'to overcome this difficulty. Further in order that the loaded,

conductor maybe still protected froni'o'xidation after leaving the furnace until it is cool, this tubeis generally prolonged,"-and may be provided with a jacket through which cold water is kept in circulation. I

The success of the annealin process is greatly influenced by the distribution and flow of the inert gas within the tube, and the object of this invention is to provide a means whereby this distribution and flow of gas may be such as to produce the best possible result. r In order to describe fully the object of the invention, it must be explained that, while it copperbecomes brittle.- But any loaded conis' necessary to prevent unduly oxidizing the loaded conductor, it is also advisable to retain such oxygen as is already included in the copper since,"without this oxygen the ductor'is liable to have upon each of its com'- .p'onent parts, a film of oil,'-which is an almost unavoidable resultof the various processes used in the manufacture. As the temp b I p h p that practlcall fall the gas m the annular,

assing."

I In order avoid i h an... an,

troduced into the tube near the oint where the wire leaves the furnace, an enters the is water-jacketed.

It will be seen that the cooling portion of the tube. The efl'ectdof thls arrangement is that the entering gas divides into two streams, one of which flows through the cooling tube and so out into the 1 atmosphere, and the other flows through the heating tube, and meeting the 'oilyfumes carries them out into the atmosphere at the end where the conductor enters the tube. v

This method however, has the disadvantage that the cold gas, meeting the surface of the conductor where it is still at or above its. critical temperature, chills with undue rapidity.-

1 Accordin to this inventionthe. heating tube,'throug which the conductor or article to be treatedis passed, is supplied with an to the commencement of the heating zone Whilea'second inlet may be situated comparatively'near the endof the heating zone..-

inert gas at two points,-,at a substantial distanee apart from one another thus oneof the gas lnlets may be situated comparatively near The gas may be supplied at these. points through a single pipe traversing a considen with the heating tube.-

.The first of said gas 'vided into a plurality of inlets and'for this v purpose a portion of f the heating tube "ad- 1 jacent the inlet end may be jacketed and provided with a number of perforations'estab' lishing communication with the space inside the jacket, to which gas'is supplied prefer- "ably through a pipe enterin the 'si eof the I jac et opposite theperforatlons in the heat-. 'ing tube.

- A second pipe ma supply of gas to the eatingtube, correspond ing to the second gas inlet. The heating tube may be extended to form When two pipes-areprovided the s upe 1y ofgas the pressure may be so adjusted eating ;tube,'is discharged into, the atmosphere at a cooling tube-which l also beprov'ided for the ieo the inlet end, whereas the gas from the second Y 7 su ply pi e passes mainly along the tu e mt e opposite directionr.

a temperature in the n'eig gases are raised to bourhood ofthat of the conductor beforecom' into contact.

heating let with'it and any traces of oilan grease upon the object undergoing treatment become volatized and are blown out into the atmosphere,

together with any particles of'dirt.

The invention is illustrated diagrammatically in Figures 1 and 2 of the accompanying drawings with reference to the annealing of a loaded telegraph-or telephone con- I ductor,jbut it should be understood that the furnace may be modified to meet other A requirements.

Referringto Figure 1 of the drawings, 1 is the furnace preferably heated by electrical The first portion of the heating tube is perforated as at 11 so that gas may pass to the 7 interior of the heating tube from the jacket. -In operation'the loaded conductor is led into the annealing tube fromthe left'hand side of the furnacel, and nitrogenis passed through the supply pipe or pipes, the pressure of which may be adjusted as desired.

What we claim is 1. A process for heat treating metals and alloys consisting in passing the article to be treated through a heating tube, and in supplying an inert gas to said tube at two points,

so that the gas supplied at one point will flow to the atmosphere at the inlet end of the heating tube and s'erveto dispel the volatil-.

ized matter offlistillation, and the gas supplied at the other point will flow to the outlet and serve to prevent oxidation and reduction of the article.

2. A. process for heat treating metals and alloys consisting in passing the article to be treated through a heating member, and in supplying an inert gas to said member at two points, the first point being substantially at the beginnin of the zone of heating, so that the gas supp ied at one point will flow to the atmosphere at the iilletend of the heating member and serve to dispel the volatilized matter of distillation, and the gas supplied at the. other point will vflow to the outlet and serve to prevent oxidation and reduction of the article. Y

3. A process for heat treating metals and alloys consisting in passing the article to be treated through a heatin tube, and in supplying an inert gas to said I spaced from each other and fronrthe' ends of the heating zone of said tube, the quantity and pressure of gas supplied being controlled so that there is no appreciable flow of gas between the two points. v

In testimony that we can claim the foregoing as. our-invention we have signed our names this 29th day of October 1925.

WILLOUGHBY 'STATHAM SMITH. HENRY JOSEPH GARNETT. JOHN ANGEL HOLDEN,

tube at'two points 

